Auto-focus apparatus, focus adjusting method, image capturing apparatus and image capturing method

ABSTRACT

An auto-focus apparatus, a focus adjusting method, an image capturing apparatus and an image capturing method make it possible to perform accurate focus adjustment on a subject for which the focus should be adjusted. The auto-focus apparatus emits an irradiation wave from emitting means for irradiation to a subject while changing an incident angle of the irradiation wave, detects an incident angle of a reflected wave of the irradiation wave reflected by the subject, incident on light receiving means positioned corresponding to the emitting means, determines based on the emitting angle and the incident angle whether or not the subject is a subject for which the focus is adjusted, and adjusts the focus on the subject when determining that the subject is the subject for which the focus should be adjusted, thereby making it possible to accurately adjust the focus on the subject for which the focus should be adjusted.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an auto-focus apparatus, a focusadjusting method, an image capturing apparatus and an image capturingmethod, and more particularly, is suitably applied, for example, to avideo camera.

[0003] 2. Description of the Related Art

[0004] Conventionally, video cameras contain a so-called auto-focusfunction which automatically performs a focusing operation of a lens inaccordance with the distance to a subject (subject distance). Forrealizing such an auto-focus function, a variety of focus detectingmethods have been devised for detecting a defocused state, and amongothers, an image processing method, an infrared method and a phasedifference detecting method are representative.

[0005] The image processing method picks up a central region from animage captured by an imaging device (CCD: Charge Coupled Device),extracts high frequency components from the picked-up region, and addsthe high frequency components to generate a value which is used as anevaluation value for detecting the focus. This evaluation value becomeshigher as an image of a subject being captured approaches a focusedstate, and becomes lower as the image is further away from the focusedstate after it presents the highest value at the position of the focusedstate. Therefore, the image processing method moves the focus to examinewhether the evaluation value increases or decreases, and adjusts thefocus while moving the focus in a direction in which the evaluationvalue becomes higher until the focused state is reached. In other words,the image processing method performs a so-called hill climbingoperation.

[0006] This image processing method is advantageous in that it canrealize an auto-focus function without modifying or adding the design ofthe optical system such as lenses, and can improve the sensitivity to afocus error since the focus is adjusted using an image captured by theCCD.

[0007] Next, the infrared method applies the principles of triangulationto calculate the subject distance. Specifically, the infrared methodirradiates an infrared ray from a video camera to a subject, detects anincident angle of return light reflected by the subject and returning tothe video camera, and then calculates the subject distance based on thedetected incident angle of the return light. The infrared method isadvantageous in that the subject distance can be sufficiently measured,even if the subject is dark, as long as the amount of return light fromthe subject exceeds a predetermined amount, since the infrared rayemitted from the video camera itself is irradiated to the subject.

[0008] Further, the phase difference detecting method provides two setsof lens groups, each comprised of a small lens and a line sensor fordetecting the position of light, in a lens optical system of a camera,and disposes the two sets of lens groups with their optical axes shiftedfrom each other to realize the aforementioned triangulation. This phasedifference detecting method is advantageous in that the capability ofdetecting a focusing state is constant irrespective of the subjectdistance.

[0009] The aforementioned image processing method, however, cannotdetect a focusing stage unless the focus is moved to examine a change inevaluation value. Also, since the evaluation value varies in response toa small movement of a subject in the vertical direction with respect tothe optical axis, the focused position can be erroneously detected.Therefore, the image processing method experiences difficulties inmaking the focus smoothly follow movements of the subject in thedirection of the optical axis.

[0010] As a solution for the problems of the image processing method,the infrared method and the phase difference detecting method have beenproposed. Since these methods can reveal a focusing state without movingthe focus, they need not move the focus to examine the focusing state.In addition, even if a subject moves in the vertical direction withrespect to the optical axis, these methods will never erroneouslymeasure the subject distance. However, because of its limited ability ofmeasuring a distance of only about 10 m or less, the infrared method isnot suitable for a business-use video camera which may capture asubject, for example, at a distance exceeding 10 m with a small depth offield (a range centered on the subject in which the subject is infocus).

[0011] Also, in the infrared method, since an optical system foremitting an infrared ray is generally disposed external to a videocamera, the optical axis of the video camera cannot be aligned with theoptical axis of the infrared ray, causing a problem of discrepancybetween an actual screen range and a range viewed in a view finder,i.e., parallax.

[0012]FIG. 1 shows the principles as to how the parallax occurs. Asshown in FIG. 1, a video camera 1 comprises a camera body 1A, and acamera lens 1B, an infrared ray emitter 1C and a return light incidentangle detector 1D mounted on the camera body 1A, and applies theprinciples of triangulation to measure the subject distance.

[0013] Since the camera lens 1B is spaced from the infrared raygenerator 1C by a predetermined distance, the optical axis A1 of aninfrared ray is not coaxial with the optical axis A2 of the camera. Inthe video camera 1, since the optical axis A1 of the infrared ray isoffset from the optical axis A2 of the camera in this way, even if asubject B1 to be captured is located on the optical axis A2 of thecamera, the infrared ray may be irradiated to a subject B2 which islocated on an axis offset from the optical axis A2 of the camera, i.e.,on the optical axis A1 of the infrared ray.

[0014] In this event, the video camera 1 detects return light L1 fromthe subject B2, which is not to be captured, to measure the distance tothe subject B2, and fails to measure the distance to the subject B1 tobe captured.

[0015] The phase difference detecting method, on the other hand, suffersfrom a lower ability of measuring the subject distance as an iris of acamera lens is reduced. Specifically, since a video camera performs anauto-focus operation and an imaging operation simultaneously, the videocamera cannot open the iris in the auto-focus operation and reduces theiris during the imaging operation, as does a still camera whichseparately performs the auto-focus operation and the imaging operation.Thus, due to the requirement of adjusting the iris during the imagingoperation, the video camera cannot avoid a degradation in the ability ofmeasuring the distance to a subject, resulting from the reduced iris.

SUMMARY OF THE INVENTION

[0016] In view of the foregoing, an object of this invention is toprovide an auto-focus apparatus, a focus adjusting method, an imagecapturing apparatus and an image capturing method which are capable ofaccurately adjusting the focus on a subject to be captured.

[0017] The foregoing object and other objects of the invention have beenachieved by the provision of an auto-focus apparatus, a focus adjustingmethod, an image capturing apparatus and an image capturing method inwhich an irradiation wave is emitted from emitting means for irradiationto a subject while changing an incident angle of the irradiation wave,an incident angle of a reflected wave of the irradiation wave reflectedby the subject, incident on light receiving means positionedcorresponding to the emitting means, is detected, whether or not thesubject is a subject for which the focus is adjusted is determined basedon the emitting angle and the incident angle, and the focus is adjustedon the subject when determining that the subject is the subject forwhich the focus should be adjusted, thereby making it possible toaccurately adjust the focus on the subject for which the focus should beadjusted.

[0018] The nature, principle and utility of the invention will becomemore apparent from the following detailed description when read inconjunction with the accompanying drawings in which like parts aredesignated by like reference numerals or characters.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In the accompanying drawings:

[0020]FIG. 1 is a schematic diagram used for explaining the principlesas to how parallax occurs;

[0021]FIG. 2 is a schematic diagram used for explaining a video cameraaccording to the present invention;

[0022]FIG. 3 is a schematic diagram used for explaining how the distanceto a subject is measured;

[0023]FIG. 4 is a block diagram illustrating the circuit configurationof the video camera;

[0024]FIG. 5 is a schematic diagram used for explaining how the distanceto a subject is measured;

[0025]FIG. 6 is a schematic diagram showing the relationship between anemitting angle of an infrared ray and an incident angle of return light;

[0026]FIG. 7 is a schematic diagram showing the relationship between anemitting angle of an infrared ray and an incident angle of return light;and

[0027]FIG. 8 is a flow chart illustrating a focus adjustment processingprocedure.

DETAILED DESCRIPTION OF THE EMBODIMENT

[0028] Preferred embodiments of this invention will be described withreference to the accompanying drawings:

[0029]FIG. 2 illustrates the configuration of a video camera, generallydesignated by reference numeral 10, which comprises a camera body 10A,and a camera lens 10B, an infrared ray emitter 10C as emitting means,and a return light incident angle detector 10D as incident lightdetecting means mounted at predetermined positions of the camera body10A. The video camera employs the infrared method as a focus detectingmethod, and applies the principles of triangulation to measure thedistance from the camera lens 10B to a subject, i.e., the subjectdistance.

[0030] In this embodiment, for measuring the subject distance, theinfrared ray emitter 10C can vary (scan) the optical axis A10 of aninfrared ray, i.e., the orientation of the infrared ray over an emittingangle in a range of θ1 to θu in the vertical direction.

[0031] In this event, an infrared ray scanning period is set, forexample, to {fraction (1/60)}seconds, so that the infrared ray emitter10C scans in a range of the emitting angle from θ1 to θu once for every{fraction (1/60)}seconds. Also, the infrared ray emitter 10C irradiatesthe infrared ray at a position on the optical axis A11 of the cameraspaced by a distance 0.8 m from the camera lens 10B when the infraredray is emitted at angle θ1, and irradiates the infrared ray at aposition on the optical axis A11 of the camera spaced by a distance 30 mfrom the camera lens 10B when the infrared ray is emitted at angle θu.In this way, the infrared ray emitter 10C can irradiate the infrared rayto a subject which is located on the optical axis A11 of the camera anddistanced from the camera lens 10B in a range of 0.8 to 30 m.

[0032]FIG. 3 shows how to measure the subject distance when a subjectB10 is located on the optical axis A11 of the camera. In this event, theinfrared ray emitter 10C irradiates an infrared ray L10 to the subjectB10 at an emitting angle θu. The infrared ray L10 is reflected by thesubject B10, and return light L11 from the subject B10 is incident onthe return light incident angle detector 10D at an incident angle θub.

[0033] When the subject B10 is located on the optical Axis A11 of thecamera as described above, the subject distance is uniquely determinedwhen the incident angle θub of the return light is determined.Therefore, the return light incident angle detector 10D measures theincident angle θub of the return light L11 to calculate the subjectdistance Lu based on the incident angle θub and the distance between thecamera lens 10B and the return light incident angle detector 10D. Then,the video camera 10 adjusts the focus in accordance with the thuscalculated subject distance Lu.

[0034] Here, the circuit configuration of the video camera 10 isillustrated in FIG. 4. A Central Processing Unit (CPU) 15 is mounted inthe camera body 10A to control the general operation of the video camera10. The CPU 15 periodically (for example, every 30 msec) checks whethera push switch 16, disposed external to the video camera 10, is pressed,and generates instruction data S1 for emitting an infrared ray when itdetects that the push switch 16 is pressed.

[0035] The CPU 15 sends the instruction data S1 to a digital-to-analog(DA) converter circuit 17 which converts the instruction data S1 to ananalog instruction signal S2 which is then sent to an Laser Diode (LD)driving circuit 18 in the infrared ray emitter 10C. The LD drivingcircuit 18, in response to the instruction signal S2, drives an LD 19 asa light emitting element, and applies the LD 19 with a current. Then,the LD 19 emits laser light L15 in accordance with the applied current.

[0036] The laser light L15 emitted from the LD 19 is transformed to adiverting beam L16 having a diverting angle proximal to a parallel beamby a lens 20, reflected by a mirror 21 comprised of a flat mirror, andirradiated to the space as an infrared ray L17.

[0037] In this embodiment, the infrared ray emitter 10C employs, as alight emitting element, the LD 19, referred to as an eye safe laserdiode, which is highly safe to eyes and oscillates in a 1400 nm Oband ofwavelength, and irradiates the laser light L15 with large powerexceeding 200 mW. The video camera 10, therefore, ensures the safety tothe eyes of the user, as well as can extend a measurable distance to 30m, i.e., approximately three times the conventional light emitting diodewhich is measurable up to approximately 10 m with power of 20 mW, by wayof example.

[0038] The CPU 15, upon detection of the pressed push switch 16, alsogenerates driving data S5 for driving a motor 22 coupled to the mirror21 in the infrared ray emitter 10C. The CPU 15 sends the driving data S5to a digital-to-analog (DA) converter circuit 25 which converts thedriving data S5 to an analog driving signal S6 which is then sent to amotor driving circuit 26 in the infrared ray emitter 10C. The motordriving circuit 26 drives the motor 22 based on the driving signal S6 tochange the inclination of the mirror 21, thereby allowing an infraredray L17 to be irradiated to a subject which is located on the opticalAxis A11 of the camera (FIG. 2) at a distance of 0.8 to 30 m from thecamera lens 10B.

[0039] An inclination sensor 27 is provided near the mirror 21, suchthat an inclination sensor detector circuit 28 detects the inclinationof the mirror 21 through the inclination sensor 27 to generate a mirrorinclination signal S8. Then, the inclination sensor detector circuit 28sends the mirror inclination signal S8 to an analog-to-digital (AD)converter circuit 29 which converts the mirror inclination signal S8 todigital mirror inclination data S9 which is sent to the CPU 15.Therefore, the CPU 15 can know the inclination of the mirror 21 based onthe mirror inclination data S9. In this way, the CUP 15 measures theorientation of the infrared ray L17 emitted from the infrared rayemitter 10C while changing the orientation of the infrared ray L17.

[0040] Also, the CPU 15 controls the power of the emitted infrared rayL17 in accordance with a change in the orientation of the infrared rayL17, i.e., a change in the distance from the camera lens 10B to aposition to be measured to reduce the power consumption and extend thelifetime of the LD 19. Specifically, for example, the CPU 15 sets theemission power at 200 mW when the infrared ray L17 is irradiated at adistance of 30 m from the camera lens 10B, while sets the emission powerat 2 mW when the infrared ray L17 is irradiated at a distance of 3 mfrom the camera lens 10B, thereby controlling the return light incidenton the return light incident angle detector 10D to a constant amount.

[0041] The return light L20 from a subject is incident on a lens 35 inthe return light incident angle detector 10D, and is converged by thelens 35 on a light receiving surface of a Position Sensitive Diode (PSD)36 as position detecting element. The PSD 36 generates a current inaccordance with the centroid of the magnitude of the return light L20converged on the light receiving surface, and sends the current to thereturn light incident angle detector 37.

[0042] The PSD 36 has the light receiving surface in alignment with thefocal plane of the lens 35, so that the incident angle of the returnlight L20 is uniquely determined when the position of the return lightL20 converged on the light receiving surface of the PSD 36 isdetermined. Therefore, the return light incident angle detector circuit37, serving as detecting means, detects the incident angle of the returnlight L20 based on the current supplied from the PSD 36. Then, thereturn light incident angle detector circuit 37 sends the detectedincident angle of the return light L20 to an analog-to-digital (AD)converter circuit 38 of the camera body 10A as a return light incidentangle signal S12. The AD converter circuit 38 converts the return lightincident angle signal S12 to digital return light incident angle dataS13 which is sent to the CPU 15.

[0043] The CPU 15 calculates the subject distance based on the emittingangle of the infrared ray L17 derived from the mirror inclination dataS9 and the incident angle of the incident angle L20 derived from thereturn light incident angle data S13, and sends the subject distance tothe camera lens 10B as subject distance data S15 to adjust the focussuch that the focus of the camera lens 10B is coincident with thesubject distance. For reference, the CPU 15 sends the subject distancedata S15 to the camera lens 10B every {fraction (1/60)}seconds to makethe focus smoothly follow movements of the subject.

[0044] Here, FIG. 5 shows a situation in which a subject B10 to beimaged is located on the optical Axis A11 of the camera, and a subjectB11 not to be imaged is located at a position apart from the opticalAxis A11 of the camera, wherein an infrared ray L20 is irradiated to thesubject B11 not to be imaged while the infrared ray L20 is beingscanned.

[0045] In this situation, return light L21 reflected by the subject B11is incident on the return light incident angle detector 10D at anincident angle θxb. In this event, a conventional video cameracalculates a subject distance based only on the incident angle θxb ofthe return light L21. As a result, the video camera disadvantageouslydetermines that the subject exists at a position of a point Pb on theoptical Axis A11 of the camera, and focuses at the position of the pointPb on the optical Axis A11 of the camera.

[0046] To eliminate this disadvantage, the CPU 15 (FIG. 4) of the videocamera 10 previously holds in an internal memory incident/emittingrelation data (FIG. 6) indicative of the relationship between theemitting angle of the infrared ray and the incident angle of returnlight when a subject exists on the optical Axis A11 of the camera, anddetermines whether or not the detected emitting angle of the infraredray and incident angle of the return light match the incident/emittingrelation data.

[0047] As a result, when determining that the detected emitting angle ofthe infrared ray and incident angle of the return light match theincident/emitting relation data, the CPU 15 determines that the subjectexists on the optical Axis A11 of the camera, and calculates thedistance to the subject. On the other hand, when determining that thedetected emitting angle of the infrared ray and incident angle of thereturn light do not match the incident/emitting relation data, the CPU15 determines that the subject does not exist on the optical Axis A11 ofthe camera, and that the subject is not to be imaged.

[0048] For example, in FIG. 5, when the video camera 10 changes theemitting angle of the infrared ray L20 from θ1 to θ2, the infrared rayL20 is first irradiated to the subject B11, and next to the subject B10.In this event, the return light incident angle detector 10D receivesreturn light L21 from the subject B11 to detect an incident angle θBb,and next receives return light from the subject B10 to detect anincident angle θAb, as shown in FIG. 7.

[0049] Thus, the CPU 15 (FIG. 4) is provided with position data PB (θB,θBb) of the subject B11 and position data PA (θA, θAb) of the subjectB10, and determines based on the aforementioned incident/emittingrelation data that only the subject B10 is located on the optical AxisA11 of the camera. Eventually, the CPU 15 determines the subject B10 asa subject to be imaged, and calculates the distance to the subject B10to adjust the focus.

[0050] As described above, in FIG. 8, the CPU 15, when entering a focusadjustment processing procedure RT1, proceeds to step SP1 to initiateevery {fraction (1/60)}seconds, and determines whether or not the pushswitch 16 is pressed at subsequent step SP2.

[0051] When an affirmative result is returned at step SP2, this meansthat the push switch 16 is pressed by the user, in which case, the CPU15 proceeds to step SP3, where the CPU 15 forces the LD 19 to emit laserlight L15. Conversely, when a negative result is returned at step SP12,this means that the push switch 16 is not pressed by the user, in whichcase, the CPU 15 proceeds to step SP4 to terminate the processingprocedure.

[0052] Then, the CPU 15 proceeds to step SP4, where the CPU 15 drivesthe motor 22 through the motor driving circuit 26 to change theinclination of the mirror 21 to change the orientation of the infraredray, and periodically samples the inclination of the mirror 21 derivedfrom the infrared ray emitter 10C and the incident angle of return lightderived from the return light incident angle detector 10D to store inthe internal memory sampling data comprised of the emitting angle of theinfrared ray indicated by the inclination of the mirror 21 and theincident angle of the return light thus derived.

[0053] Then, the CPU 15 turns off the LD 19 at step SP5, and proceeds tostep SP6, where the CPU 15 acts as determining means to search thesampling data for one indicative of return light from a subject locatedon the optical Axis A11 of the camera, and to calculate the subjectdistance based on the incident angle of the found return light.

[0054] Next, the CPU 15 acts as adjusting means at step SP7, where theCPU 15 notifies the camera lens 10B of the calculated subject distanceto adjust the focus such that the focus of the camera lens 10B matchesthe subject distance. Subsequently, the CPU 15 proceeds to step SP4 toterminate the processing procedure.

[0055] In the foregoing configuration, the infrared ray emitter 10Cchanges the emitting angle of the infrared ray under the control of theCPU 15 to emit the infrared ray, detects the emitting angle, andnotifies the CPU 15 of the detected emitting angle. The infrared rayemitted from the infrared ray emitter 10C is reflected by a subject andincident on the return light incident angle detector 10D. The returnlight incident angle detector 10D detects the incident angle of thereturn light from the subject, and notifies the CPU 15 of the detectedincident angle.

[0056] The CPU 15 determines based on the emitting angle of the infraredand the incident angle of the return light, detected when the infraredray is irradiated to the subject, whether or not the subject exists onthe optical Axis A11 of the camera, and calculates the subject distancebased on the incident angle of the return light from the subject whendetermining that the subject exists on the optical Axis A11 of thecamera. Then, the CPU 15 adjust the focus of the camera lens 10B usingthe calculated subject distance.

[0057] Consequently, the video camera 10 prevents the calculation of thesubject distance based on the incident angle of return light reflectedby and returned from a subject which does not exist on the optical AxisA11 of the camera, i.e., a subject not to be imaged.

[0058] According to the foregoing configuration, the infrared ray isemitted as the emitting angle thereof is changed, and it is determinedbased on the emitting angle of an infrared ray and an incident light ofits return light, which are detected when the infrared ray is irradiatedto a subject, whether or not the subject exists on the optical axis ofthe camera before the subject distance is calculated, thereby making itpossible to accurately calculate the subject distance and accomplishmore accurate focus adjustments as compared with the prior art.

[0059] While the foregoing embodiment has been described in connectionwith a flat mirror which is employed as the mirror 21 for changing theemitting angle of the infrared ray, the present invention is not limitedto this particular mirror, but can employ a mirror in any of othervarious shapes, such as a polygon mirror, by way of example.

[0060] Also, while the foregoing embodiment has been described inconnection with the PSD 36 employed as the position detecting element,the present invention is not limited to this particular element, but canemploy any of other various position detecting elements such as a bisectpin photodiode, by way of example.

[0061] Further, while the foregoing embodiment has been described for aspecific configuration in which the infrared ray is emitted as itsorientation is changed, the present invention is not limited to thisconfiguration. Alternatively, a plurality of infrared ray emitters foremitting infrared rays in different orientations from one another can beprovided such that desired one is selected and lit from the plurality ofinfrared ray emitters as required.

[0062] Further, while the foregoing embodiment has been described for aspecific configuration in which an infrared ray is irradiated to asubject to calculate the subject distance, the present invention is notlimited to this configuration. Alternatively, any of other variousirradiation waves such as ultrasonic waves, by way of example, can beirradiated to a subject to calculate the subject distance.

[0063] Further, while the foregoing embodiment has been described inconnection with the video camera 10 to which the present invention isapplied, the present invention is not limited to the video camera butcan be applied widely to a variety of other auto-focus apparatus whichcontain an auto-focus function such as a still camera for photographinga still image, by way of example.

[0064] As described above, according to the present invention, theauto-focus apparatus irradiates an irradiation wave from emitting meansto a subject while changing an emitting angle of the irradiation wave,detects an incident angle of a reflected wave of the irradiation wavereflected by the subject, incident on light receiving means positionedcorresponding to the emitting means, determines based on the emittingangle and the incident angle whether or not the subject is a subject forwhich the focus should be adjusted, and adjusts the focus on the subjectwhen determining that the subject is the subject for which the focusshould be adjusted, thereby making it possible to accurately adjust thefocus on the subject for which the focus should be adjusted.

[0065] While there has been described in connection with the preferredembodiments of the invention, it will be obvious to those skilled in theart that various changes and modifications may be aimed, therefore, tocover in the appended claims all such changes and modifications as fallwithin the true spirit and scope of the invention.

What is claimed is:
 1. An auto-focus apparatus comprising: emittingmeans for emitting an irradiation wave for irradiation to a subjectwhile changing an emitting angle of said irradiation wave; detectingmeans for detecting an incident angle of a reflected wave of saidirradiation wave reflected by said subject, incident on light receivingmeans positioned corresponding to said emitting means; determining meansfor determining based on said emitting angle and said incident anglewhether or not said subject is a subject for which the focus should beadjusted; and adjusting means for adjusting the focus on said subjectwhen determining that said subject is the subject for which the focusshould be adjusted.
 2. The auto-focus apparatus according to claim 1 ,wherein said emitting means emits an infrared ray emitted from an eyesafe laser diode.
 3. The auto-focus apparatus according to claim 1 ,wherein said emitting means controls emission power of said irradiationwave in accordance with a change in the emitting angle of saidirradiation wave.
 4. The auto-focus apparatus according to claim 1 ,wherein said determining means comprises a storage means for storingsampling data of said emitting angle and said incident angle.
 5. Theauto-focus apparatus according to claim 4 , wherein said determiningmeans comprises a storage means for storing correspondence data of saidemitting angle and said corresponding incident angle.
 6. A focusadjusting method comprising the steps of: emitting an irradiation wavefrom irradiating means for irradiation to a subject while changing anemitting angle of said irradiation wave; detecting an incident angle ofa reflected wave of said irradiation wave reflected by said subject,incident on light receiving means positioned corresponding to saidemitting means; determining based on said emitting angle and saidincident angle whether or not said subject is a subject for which thefocus should be adjusted; and adjusting the focus on said subject whendetermining that said subject is the subject for which the focus shouldbe adjusted.
 7. The focus adjusting method according to claim 6 ,wherein said emitting means emits an infrared ray emitted from an eyesafe laser diode.
 8. The focus adjusting method according to claim 6 ,wherein said emitting means controls emission power of said irradiationwave in accordance with a change in the emitting angle of saidirradiation wave.
 9. The focus adjusting method according to claim 6 ,wherein said determination is made based upon stored sampling data ofsaid emitting angle and said incident angle.
 10. The focus adjustingmethod according to claim 6 , wherein in said determination, saidsampling data is selected based upon stored correspondence data of saidemitting angle and said corresponding incident angle.
 11. An imagecapturing apparatus comprising: emitting means for emitting anirradiation wave for irradiation to a subject while changing an emittingangle of said irradiation wave; detecting means for detecting anincident angle of a reflected wave of said irradiation wave reflected bysaid subject, incident on light receiving means positioned correspondingto said emitting means; determining means for determining based on saidemitting angle and said incident angle whether or not said subject is asubject for which the focus should be adjusted; and adjusting means foradjusting the focus on said subject when determining that said subjectis the subject for which the focus should be adjusted.
 12. The imagecapturing apparatus according to claim 11 , wherein said emitting meansemits an infrared ray emitted from an eye safe laser diode.
 13. Theimage capturing apparatus according to claim 11 , wherein said emittingmeans controls emission power of said irradiation wave in accordancewith a change in the emitting angle of said irradiation wave.
 14. Theimage capturing apparatus according to claim 11 , wherein saiddetermining means comprises a storage means for storing sampling data ofsaid emitting angle and said incident angle.
 15. The image capturingapparatus according to claim 14 , wherein said determining meanscomprises a storage means for storing correspondence data of saidemitting angle and said corresponding incident angle.
 16. An imagecapturing method comprising the steps of: emitting an irradiation wavefrom irradiating means for irradiation to a subject while changing anemitting angle of said irradiation wave; detecting an incident angle ofa reflected wave of said irradiation wave reflected by said subject,incident on light receiving means positioned corresponding to saidemitting means; determining based on said emitting angle and saidincident angle whether or not said subject is a subject for which thefocus should be adjusted; and adjusting the focus on said subject whendetermining that said subject is the subject for which the focus shouldbe adjusted.
 17. The image capturing method according to claim 16 ,wherein said emitting means emits an infrared ray emitted from an eyesafe laser diode.
 18. The image capturing method according to claim 16 ,wherein said emitting means controls emission power of said irradiationwave in accordance with a change in the emitting angle of saidirradiation wave.
 19. The image capturing method according to claim 16 ,wherein said determination is made based upon stored sampling data ofsaid emitting angle and said incident angle.
 20. The image capturingmethod according to claim 19 , wherein in said determination, saidsampling data is selected based upon stored correspondence data of saidemitting angle and said corresponding incident angle.